Function RoundDown

cpp/src/arrow/util/bit_util.h:96–98

Returns 'value' rounded down to the nearest multiple of 'factor'

// Returns 'value' rounded down to the nearest multiple of 'factor'
constexpr int64_t RoundDown(int64_t value, int64_t factor) {
  return (value / factor) * factor;
}

// Returns 'value' rounded up to the nearest multiple of 'factor' when factor
// is a power of two.